[llvm] Simplify `(a % b) lt/ge (b-1)` into `(a % b) eq/ne (b-1)` (PR #72504)

[Nikita Popov via llvm-commits]

nikic wrote:

Reverted in https://github.com/llvm/llvm-project/commit/de8f782355842a5d3ad44ad8861c53e3ef6fa73a. It looks like not all tests were updated.

(I did check the pre-commit results, but they failed due to an unrelated Flang issue and for some reason we do not run LLVM tests if Flang tests fail -- WTF?)

https://github.com/llvm/llvm-project/pull/72504